Algeco had a considerable fleet of 45 ton Gross laden weight tank wagons. TOPS numbered them from 49000 onwards, but Class A, Class B and LPG tanks were mixed within this series. They also had different builders, so details differed between batches. These are for liquified petroleum gas, butane and propane, hired to SMBP. The period of the photographs is during the transition from SMBP to separation for Shell and BP. The running numbers were, unusually, at the right hand of the barrel and none appear to have carried a TOPS code. They were rebuilt in the mid 1980s, and became part of the BP fleet, 59598/9, 660- 683. see http://PaulBartlett.zenfolio.com/smbplpg